Battery monitoring objectives may be summarized as a) providing accurate and timely information on the battery reserve time, b) providing accurate and timely information on remaining battery life, c) providing recommendations to the optimal charging process that will allow for efficient charge recovery without sacrificing battery health, and d) informing the user on any possible maintenance action that supports system integrity. To meet these objectives continuous monitoring of real-time battery variables and trend data should take place. However, some battery monitors are still based on simple data logging that is supported by limit sensing. Centralized approaches in cell, or bloc, signal sensing is still dominant in the existing systems. Furthermore, a good part of the in formation extraction scenarios are far from being automated with most of the analysis being operator driven and test conducted on a periodic basis.
Efficient management of a battery network requires the smooth flow of timely and consistent information/data from the battery units (blocs, groups, strings and banks) to the various monitoring, management and control sites. The main issue related to implementing of real-time battery monitoring is voltage, temperature and current measurement. In particular, the ability to acquire accurate and timely voltage measurement is critical. The accuracy and resolution of the voltage measurement directly impacts on the accuracy and resolution of the derived information. This is especially important for capacity estimation utilizing the Coup De Fouet region. For thorough implementation (down to bloc level), the system is required to monitor the voltage of each bloc at the start of discharge at a frequency of up to 1 Hz.
However, battery networks vary in size. Systems could be as small as two strings of 24V mono-blocs. On the other hand, large systems could have tens of strings containing 24 blocs each. Normal practice is to partition the battery into a number of four string banks. Each string may contain blocs that are 2, 4, 6, or 12 volts. The 12-volt may be used as the common grouping factor that promotes relating the adjacent cells, whether they are six cells within a 12-volt mono-bloc or six individual adjacent blocs. The result is the need for substantial amounts of information to be acquired and processed in real-time. This causes consideration traffic overflow within the monitoring network in the case of centralizing the data processing.
Recently, the Internet connectivity to the site has also been encouraged. The approach presented is based on site-central connectivity. One approach is presented by O. Ludin in “An Operation and Maintenance Process Model for Energy Management” [Proceedings of the 21th International Telecommunication Energy Conference; Jun. 6-9, 1999, Copenhagen, 28-1 (7 pages)] which is based on the site as a Simple Network Management Protocol (SNMP) agent that interacts with the remote station using what is called energy management application software. Another approach is described in “Controlling and Alarming DC Power Plants via the Internet” [Proceedings of the 20th International Telecommunication Energy Conference; Oct. 4-8, 1998, San Francisco, PP 617-22, A. Cosentino & M. Sullivan] which implements the connectivity using a gateway that is based on an embedded PC operated by QNX real time operating system. However, both solutions are cost sensitive and limit the site to a central connection point.
A battery monitoring network is described in U.S. Pat. No. 6,104,967. A number of modules communicate with a central battery computer. The modules each include module computers which monitor various operations and status conditions within the module, including potential, current, and temperature conditions.
It is an object of the present invention to provide a generic network architecture for a battery monitoring system which can be implemented on existing open standard network protocols, is cost effective and efficient, and is inherently suited to internet connectivity; or to provide a system which at least overcomes or ameliorates some of the disadvantages with the prior art, or provides industry with a useful alternative.
Further aspects of the invention will become apparent from the following description.